In Australia in March 2006, we are almost five weeks into the 10-week Biggest Loser series. One contestant Wal, lost 27kgs in the first three weeks. That's an average of 9 kg a week. Whilst this impressive figure is sure to provide motivation for many viewers, it may also promote unsafe rapid weight loss and set up false expectations for weight loss results.

Love it or hate it, the Biggest Loser provides an insightful window into how people lose weight (read subscriber comments and share yours at the end of this article). Between these opinions, there are some useful lessons for eating, exercise, motivation and long-term success. As part of my research on weight loss, I've been tuning in to Channel 10 at 7pm most weeknights. Here's Part 1 of my lowdown on the Biggest Loser.

Weight loss

How can someone lose 15.5 kilograms in a week? That's a Biggest Loser record according to Blue Team Trainer, Bob Harper.

Wal's dramatic first week weight loss of 15.5 kg can be partly explained by an artificially high starting weight. The contestants feasted on their 'last supper' before their first weigh-in, so Wal and the other contestants could conceivably have been carrying 3-4 kg of extra food and drink onto the scales.

On the first day, the contestants entered their boot camp fully (or more likely, overly) nourished so they would have been carrying their highest levels of muscle glycogen, fluid and body fat. By the time they reached the second weigh-in a week later, they would have lost a substantial amount of muscle glycogen, due to the carbohydrate-limited diet.

Muscle glycogen is where we store the carbohydrate we eat. For every gram of carbohydrate we store in glycogen, we also store two to three grams of water. Depleting glycogen stores by up to 500 g will therefore result in a fluid loss of about 1500 g. So, that's another 2 kg weight loss.

Losses of body fat could account for another kilo or two, bringing potential weight loss to around a total of 8 kg in the first week.

If contestants attempt to minimize their fluid or body water by not drinking or eating much the day before or the day of the next weigh-in they could also cut back another kilogram weight.

In Week 4, Wal showed just how easy it is to manipulate body weight with fluid intake. At the Week 4 weigh-in Wal anticipated that the Red Team would choose him to not have his weight loss counted in his team's weekly total. He only lost half a kilo, which he said was because he drank three litres of water and ate half a kilo of yoghurt the night before. Wal is now set for a bigger weight loss the following week.

And it seems that other contestants may be playing the game by loading up on water before weigh-ins. The March 4-10 TV Week which headlines “Cheating Plans Exposed”, highlights the intense competition:

“In weeks to come, we'll see contestants taking advantage of the false weight that `loading up' with water provides. In weeks when they have immunity, Losers drink litres of water before the weigh-in. Then, the following week, they have a higher percentage of weight loss from the inflated total. Suprisingly, the trainers actually encourage this strategy.”

In TV Week, eliminated contestant David reveals more manipulation:

“People on the blue team decided that they would get up at 3am and do some training before the 5am weigh-in… When Jillian (Red Team Trainer) found out, she blew up. It was a health issue. But it's competitive, and if you think you can drop a few kilos, people will take advantage of that.”

Lessons from the Biggest Loser:

When starting a weight loss program you can drop weight quickly, but most of the initial weight loss will be fluid and muscle. Be prepared for the numbers to get smaller as you progress.

A weekly weight loss of 250-500 g is still significant and heading in the right direction.

Rapid results on the scales can provide a motivational boost. This is why many weight loss programs prescribe a 'quick start' or 'quick loss' phase.

If you are prepared to lose weight slowly, you'll be less likely to feel that you are depriving yourself of food or need to do strenuous exercise. For some people this will be an easier, safer and more successful approach.

Weight loss plateaus are normal and expected. When the scales don't change for a few weeks keep maintaining positive diet and exercise habits.

Body composition

In the first week, Harry lost 12.2 kg, but how much of this was fat? The amount of body fat the contestants are losing remains a mystery. The competition is based on weight loss, not body fat loss so we know nothing about how much muscle the contestants are losing or gaining during the program.

Fat loss should only account for a small proportion of the weight losses in the first one to two weeks. As the program progresses, weight losses are smaller. Weight losses in subsequent weeks will be closer to representing actual body fat losses. Harry only lost 1.3 kg in Week 4. Disappointed at the prospect of being voted out, he said “Your body catches up with you and you go into shock.” Even so, Harry's 1.3 kg loss is still higher than what many people at home may achieve after four weeks.

Knowing body composition figures (% body fat and muscle) would be interesting, as energy restricted diets can cause loss of muscle mass in addition to body fat loss. When the body is a state of semi-starvation, fat loss reaches a maximum and the energy shortfall is met by breaking down body protein.

A rapid diet-only weight loss program, like many of the quick-fix diets available, runs the risk of depleting your muscles as well as your fat stores. The result is faster and more dramatic weight loss, but not the type of weight you want to see come off. As you drop muscle as well as fat, your metabolic rate will fall and inevitably lead to an early plateau. If you then ditch the diet and return to your previous higher-calorie eating habits, you're likely to gain body fat to a level greater than when you started.

For Biggest Loser contestants, two factors may slow down or avoid muscle losses. One is the weight training exercises which will stimulate muscle growth, or at least muscle retention. The other is the relatively high protein diet, which will provide amino acids to build their muscles.

Lessons from the Biggest Loser:

Focusing on weight alone won't show you whether you are losing fluid, muscle or body fat.

If you gain muscle at the same time you lose body fat you may see no change in weight loss. This can be disheartening.

If you don't see the number on the scales fall, but you do feel that your clothes are loosening you will be losing body fat. Don't be disheartened with your progress.

Health

Even if contestants lose a substantial amount of muscle during the 10-week program, at their size, they will be doing their health a big favour.

When the Biggest Loser contestants started, they were all classified as obese with a Body Mass Index (BMI) over 30. The heaviest contestant and the first to be voted out, David started at 196 kg, placing him in the morbidly obese category.

Time will tell whether he achieves a healthy BMI of between 20-25, but even if he doesn't, he will experience substantial health benefits from weight loss. According to Scottish Obesity Guidelines (1996), a 10 kg weight loss is expected to deliver the following risk factor reductions:

These figures are worth remembering as they provide good motivation for even a modest weight loss for someone who is obese.

Mortality is a strong motivator for many contestants. They appear genuinely concerned that they won't be around to play with their children if they don't do something about their weight. In contrast, for viewers who initially weigh in within a healthy weight range, or slightly above but without risk factors, there is no need to aim for the dramatic weight losses achieved by contestants. Simply halting an upward creep in body weight or dropping a couple of kilos are useful targets to stay healthy.

Lessons from the Biggest Loser:

If you are obese, losing 10 kg or around 10% of body weight will offer health benefits.

Even without weight loss, becoming a regular exerciser will improve your health dramatically. Research from the Cooper Institute in the US shows that someone who is overweight, but exercises, can have a lower health risk than someone who is normal weight but does no exercise.

Ditching fatty fast food, limiting sugary treats and cutting back on alcohol will also boost your health even when you are losing weight slowly.

Diet

Specifics of the Biggest Loser diet are sketchy. We see contestants eating vegetables and fruit, but are given little idea of what makes up their diet. Perhaps, because the diet will be revealed at the end of the program along with a Biggest Loser book promotion!

Well, you don't have to wait another five weeks as the US program's book is available now in some Australian book stores. There's also a copy of a Biggest Loser 5-Day Diet you can download from the Australian website - Biggest Loser.com.au

Although the sample diet doesn't provide details of how diets are tailored for individual contestants, it does show a basic plan. Here's the breakdown of the sample Biggest Loser 5-Day Diet:

So how would you describe this diet? It's a high-protein, low-fat, carbohydrate-limited diet. It provides around 5,000 kJ per day, which is what almost all basic weight loss diets contain. The basic CSIRO Total Wellbeing Diet has 5,500 kJ.

Contestants may have been eating and drinking well over 10,000 kJ before the program, so cutting back calories by 50% explains the results they are achieving.

Carbohydrate is limited to 138 g, which is above the 100 g threshold that is often regarded as the point at which you'll experience ketosis. This is a state where your body is getting insufficient carbohydrate to provide your brain with sugar. At this point fat burning is accelerated, but so too is loss of lean muscle.

The diet provides 30 g of dietary fibre, which is the minimum target recommended by health authorities. Vegetables provide the majority of the fibre.

Vitamin and mineral levels in the diet are generally above 100% of the RDIs (Recommended Dietary Intakes). However, you only get 81% of the RDI for zinc. Lean protein foods such as red meat, fish and chicken provide zinc, as do cereals like rolled oats, unprocessed bran and rice. More cereals would help meet the 100% RDI target.

Lessons from the Biggest Loser:

Cutting energy to around 5,000 kJ per day will result in weight loss in most people, irrespective of ratio of fat, carbohydrate and protein.

Consuming less than 5,000 kJ is generally not recommended as it's very difficult to get enough vitamins and minerals.

The higher protein content may help curb appetite, which is the major benefit of protein in a weight loss diet.

The long-term success of any diet is based on your ability to stick to it. The diet you follow is only one component of a successful weight loss program.

Managing meal timing, eating triggers, social eating, emotional eating and other factors that tend to put you off-track are increasingly important as your weight loss program progresses.